On Friday, the Supreme Court announced that it would hear challenges to President Donald Trump’s executive order to end birthright citizenship. The 14th Amendment automatically makes all babies born on American territory citizens. Trump’s effort to overturn the traditional reading of the constitutional text and history should not succeed. Ratified in 1868, the 14th Amendment provided a constitutional definition of citizenship for the first time. It declares that "all persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the state wherein they reside." In antebellum America, states...